Fix stale app UI (supabase) & overall E2E test infra improvements (#337)

Fixes #269

src/preload.ts

@@ -76,7 +76,12 @@ const validInvokeChannels = [
   "rename-branch",
   "clear-session-data",
   "get-user-budget",
-] as const;
+  // Test-only channels
+  // These should ALWAYS be guarded with IS_TEST_BUILD in the main process.
+  // We can't detect with IS_TEST_BUILD in the preload script because
+  // it's a separate process from the main process.
+  "supabase:fake-connect-and-set-project",
+];
 
 // Add valid receive channels
 const validReceiveChannels = [